Neural stimulators are used to treat a variety of disorders, such as epilepsy, obesity, and breathing disorders. Experimentally, neural stimulation has been shown to have a significant effect on several cardiovascular conditions, and has been proposed to treat hypertension, post myocardial infarction (MI) remodeling and heart failure.
Hypertension is a cause of heart disease and other related cardiac co-morbidities. Hypertension occurs when blood vessels constrict. As a result, the heart works harder to maintain flow at a higher blood pressure, which can contribute to heart failure. A large segment of the general population, as well as a large segment of patients implanted with pacemakers or defibrillators, suffer from hypertension. The long term mortality as well as the quality of life can be improved for this population if blood pressure and hypertension can be reduced. Many patients who suffer from hypertension do not respond to treatment, such as treatments related to lifestyle changes and hypertension drugs.
Direct electrical stimulation has been applied to afferent nerve trunks, including the vagus nerve and carotid sinus. Research has indicated that electrical stimulation of the carotid sinus nerve can result in reduction of experimental hypertension, and that direct electrical stimulation to the pressoreceptive regions of the carotid sinus itself brings about reflex reduction in experimental hypertension. Electrical systems have been proposed to treat hypertension in patients who do not otherwise respond to therapy involving lifestyle changes and hypertension drugs, and possibly to reduce drug dependency for other patients. The stimulation of sympathetic afferents triggers sympathetic activation, parasympathetic inhibition, vasoconstriction, and tachycardia. In contrast, parasympathic activation results in bradycardia, vasodilation and inhibition of vasopressin release.
Neural stimulators that rely on continuous or intermittent open-loop stimulation do not adapt to physiologic changes during therapy.